Keller was born March 21, 1982, in Las Vegas, Nevada to mother Karen and father Kelly. Both parents were intercollegiate athletes at Arizona State University; his father played basketball and his mother swam. His older sister Kelsey swam for University of Washington, and younger sister Kalyn swam for University of Southern California (USC) and competed at the 2004 Summer Olympics.
Klete Derik Keller (born March 21, 1982) is an American former competition swimmer who won medals at the 2000, 2004, and 2008 Summer Olympics in the 400-meter freestyle and the 4×200-meter freestyle relay.
Keller grew up in Phoenix, Arizona. Keller graduated from Arcadia High School in 2000.
Having left in 2001 to focus on swimming, he returned to USC in 2007 to complete his bachelor degree. He was originally studying science and public policy. He, at one point, was studying construction management. He ultimately received his degree in public policy and real estate development, having attended both USC and Eastern Michigan University for his college education. Keller would later recount that he had, ahead of the 2008 Summer Olympics, considered instead attending Arizona State University in order to study criminology.
During the 4×200-meter freestyle relay in the Athens Summer Olympics in 2004, Keller held off a charging Ian Thorpe in the anchor leg to win the race by 0.13 seconds. This was the first time Australia had been beaten in the event in over seven years. In January 2016, Andy Ross of Swimming World named it as one of the greatest Olympic relays of all-time.
From 2004 to 2007, Keller trained at Club Wolverine, run at the University of Michigan in Ann Arbor under Jon Urbanchek and later Bob Bowman. Urbanchek would also be the coach of the three Olympic swimming teams which Keller competed on. In 2007, Keller left Ann Arbor and returned to USC to finish school and train under coach Dave Salo.
After his swimming career, Keller worked a series of jobs in sales and finance. In February 2013 he began working at the Memphis, Tennessee office of Cantor Fitzgerald as a debt trader. He would, in 2018, reflect on his career in sales and debt trading in an interview that, "Swimmer had been my identity for most of my life, and then I quickly transitioned to other roles and never gave myself time to get comfortable with them. I really struggled with things. I didn't enjoy my work, and that unhappiness and lack of identity started creeping into my marriage." In an interview years later for a podcast by the Olympic Channel, Keller commented on his performance as an employee at this time, saying that he had set high expectations for himself, but had been "entitled" in the workplace, as well as a bad employee.
In 2018, Keller revealed that in January 2014, after going through both his divorce and becoming unemployed, he had become homeless and lived out of his car for roughly ten months (managing to shower at a gym, where he still had a membership). He also said that, for four years, he lacked visitation rights with his children, making him unable to see them, despite living only minutes away from them. In an interview he conducted in the spring of 2014, he stated that he was no longer certain of the whereabouts of three of his Olympic medals. In the same 2014 interview, Keller also said that he had failed to find similar successes in his endeavors after retiring from swimming. He said that he made the mistake of not having the foresight to plan for his post-swimming career, and felt somewhat "bitter" both towards himself and his sport. He expressed regret for having continued swimming for another four years after the 2004 Olympics, saying that he believed, in retrospect, that he should have retired after the 2004 Summer Olympics and gone back to school thereafter.
In 2015, the Reno Gazette-Journal named Keller as the most decorated Olympian ever born in Nevada.
In 2018, Keller credited his sister Kalyn with having assisted him with what he saw as a personal comeback from his low-point of homelessness, saying that she had taken him in. He said that during this personal comeback, he made a living by teaching swimming lessons and operating swim clinics.
Since 2018, Keller has resided in Colorado Springs. Keller began a career there as a real estate broker, being employed as an independent contractor with the real estate firm Hoff & Leigh. In 2021, when SwimSwam contacted them for their January 11 story reporting Keller's involvement in the storming of the Capitol, Hoff & Leigh confirmed that Keller was still an employee of the firm. The SwimSwam reporter that broke the story commented in their article that the firm "seemed unaware of the Capitol video or Keller's possible involvement" in the storming of the Capitol. Later that day, the firm erased all mentions of Keller from its website. On January 12, 2021, Hoff & Leigh released a statement saying that Keller no longer worked for the company, having resigned, and that they did not condone his actions.
In January 2021, Keller was arrested and charged with three offenses stemming from his presence at the 2021 storming of the United States Capitol.
It was reported in early 2021 that Keller recently had become engaged.